U.S. patent application number 12/731365 was filed with the patent office on 2010-10-07 for led bulb.
This patent application is currently assigned to LIQUIDLEDS LIGHTING CORP.. Invention is credited to KUN-YUAN CHIANG.
Application Number | 20100253221 12/731365 |
Document ID | / |
Family ID | 42306613 |
Filed Date | 2010-10-07 |
United States Patent
Application |
20100253221 |
Kind Code |
A1 |
CHIANG; KUN-YUAN |
October 7, 2010 |
LED BULB
Abstract
An LED bulb uses an LED strip suspended between two lead frames
of a stem as a light source to provide uniform illumination with
wider angles. The lead frames of the stem provide an improved
structural stability to the LED strip while maintaining a reliable
electrical connection between the components of the stem and the
LED strip. The utilization of both top-emitting and side-emitting
LEDs on the LED strip further allows lights emitted in directions
substantially parallel and perpendicular to the LED strip to cover
a wide angle of illumination from the LED bulb.
Inventors: |
CHIANG; KUN-YUAN; (Taipei
City, TW) |
Correspondence
Address: |
ROSENBERG, KLEIN & LEE
3458 ELLICOTT CENTER DRIVE-SUITE 101
ELLICOTT CITY
MD
21043
US
|
Assignee: |
LIQUIDLEDS LIGHTING CORP.
GEORGE TOWN
KY
|
Family ID: |
42306613 |
Appl. No.: |
12/731365 |
Filed: |
March 25, 2010 |
Current U.S.
Class: |
315/32 ;
313/318.01 |
Current CPC
Class: |
F21Y 2115/10 20160801;
F21K 9/232 20160801; F21Y 2107/90 20160801; F21K 9/00 20130101;
F21V 17/101 20130101; Y10S 362/80 20130101; F21V 3/02 20130101;
F21Y 2107/00 20160801 |
Class at
Publication: |
315/32 ;
313/318.01 |
International
Class: |
H01K 1/62 20060101
H01K001/62; H01J 5/48 20060101 H01J005/48 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 2, 2009 |
TW |
098110990 |
Claims
1. An LED bulb, comprising: a bulb base; a housing having a cavity
and an end opening; a stem having a first lead frame and a second
lead frame extending into the cavity and electrically connected to
the bulb base; a member joined to the bulb base and the housing;
and at least one LED strip suspended between the first and second
lead frames and having a first electrode and a second electrode
electrically connected to the first and second lead frames
respectively, wherein each of the at least one LED strip comprises:
a substrate; a plurality of top-emitting LEDs mounted on the
substrate, having a light-emitting direction substantially
perpendicular to the substrate; and a plurality of side-emitting
LEDs mounted on the substrate, having a light-emitting direction
substantially parallel to the substrate.
2. The LED bulb of claim 1, wherein the side-emitting LEDs are
mounted on the substrate of the at least one LED strip in a manner
surrounding the top-emitting LEDs mounted thereon.
3. The LED bulb of claim 2, wherein the side-emitting LEDs are
mounted in a peripheral region of a mounting surface of the
substrate so as to emit light in multiple directions substantially
parallel to the mounting surface of the substrate.
4. The LED bulb of claim 1, wherein the substrate comprises a
double-sided circuit board having a first mounting surface with a
first group of the top-emitting and side-emitting LEDs, and a
second mounting surface opposite to the first mounting surface and
with a second group of the top-emitting and side-emitting LEDs.
5. The LED bulb of claim 1, wherein the substrate comprises: a
first single-sided circuit board having a first mounting surface
with a first group of the top-emitting and side-emitting LEDs; and
a second single-sided circuit board having a second mounting
surface with a second group of the top-emitting and side-emitting
LEDs; wherein the first and second single-sided circuit boards are
attached to each other in a back-to-back manner.
6. The LED bulb of claim 1, wherein the substrate comprises a first
conductor and a second conductor electrically connected to the
first and second electrodes of the at least one LED strip
respectively, to provide power to the top-emitting LEDs and the
side-emitting LEDs mounted thereon.
7. The LED bulb of claim 6, wherein the first and second conductors
are coplanar to a mounting surface of the substrate.
8. The LED bulb of claim 6, wherein the first and second conductors
are on a first mounting surface and a second mounting surface
opposite to the first mounting surface of the substrate
respectively.
9. The LED bulb of claim 1, wherein the top-emitting LEDs and the
side-emitting LEDs comprise: a first lighting group having a first
circuitry forward biased from the first lead frame to the second
lead frame in response to a positive half cycle of a power source
electrically connected thereto via the bulb base; and a second
lighting group having a second circuitry forward biased from the
second lead frame to the first lead frame in response to a negative
cycle of the power source electrically connected thereto via the
bulb base.
10. The LED bulb of claim 9, wherein the first and second lighting
groups of the top-emitting LEDs and side-emitting LEDs are on
opposite mounting surfaces of the substrate respectively.
11. The LED bulb of claim 9, wherein the first and second lighting
groups of the top-emitting LEDs and side-emitting LEDs are on an
upper potion and a lower portion of the substrate respectively.
12. The LED bulb of claim 1, wherein the at least one LED strip
comprises more than two LED strips suspended between the first and
second lead frames of the stem.
13. The LED bulb of claim 1, wherein the first and second lead
frames of the stem are of a slender shape having an upper width
greater than a lower width thereof, and both the upper and lower
widths are smaller than or equal to a width of the end opening of
the housing.
14. The LED bulb of claim 1, wherein the first lead frame of the
stem extends into the cavity of the housing away from the second
lead frame of the stem at a distance greater than or equal to a
length of the substrate of the at least one LED strip.
15. The LED bulb of claim 1, further comprising a power control
unit electrically connected between the bulb base and the second
lead frame of the stem.
Description
FIELD OF THE INVENTION
[0001] The present invention is related to a light bulb and, more
particularly, to a light-emitting diode (LED) bulb that may be used
as a replacement light bulb.
BACKGROUND OF THE INVENTION
[0002] Conventional incandescent bulbs mostly include a conductive
filament, such as a tungsten filament, supported by lead frames
which are connected to an external power source via a bulb base to
supply electricity to the filament. The filament is rendered
incandescent by current flowing therethrough and thus generates
light that radiates outward uniformly and extensively. The
conventional incandescent bulb, though capable of a wide lighting
angle, is disadvantageous because of its high power consumption,
high temperature, and short lifetime. By contrast, a light-emitting
diode (LED) bulb has a long lifetime, is power saving, produces no
wastes that may cause pollution, and is therefore environmentally
friendly. Hence, LED bulbs are gradually replacing the conventional
incandescent bulbs and are regarded as the new generation lighting
devices. However, the limited lighting angle and high production
costs of LED bulbs have restricted their applicability in our daily
lives.
[0003] U.S. Patent Application Publication No. 2005/0254264
discloses an LED bulb which includes a bent circuit board mounted
with LEDs thereon, to provide more extensive and uniform
illumination in a three-dimensional space by arranging each of the
LEDs to have a light-emitting direction perpendicular to the bent
circuit board. However, this LED bulb still has its drawbacks such
as high production costs, difficult assembly, and a hard-to-control
yield. In addition, a wide lighting angle is unattainable if fewer
LEDs are used. Moreover, to expose heat radiating ribs, the circuit
board cannot enclose the lateral sides and thus, there will be no
LEDs at the lateral sides. Consequently, the LED bulb cannot
provide effective lateral illumination.
[0004] On the other hand, while it is common practice to connect
several through-hole LEDs together for multi-angle light emission,
the slender pins typical of commercially available through-hole
LEDs tend to cause lack of stability and reliability in the
resultant mechanical structure. The multi-angle illumination is
achieved by bending the pins of LEDs to different directions, and
thus the overall structural stability of the finished product will
be even lower. The connection between the pins of LEDs may also be
problematic. For instance, short circuit and safety hazards may
arise from improper arrangement or spacing between the pins when
they are electrically conducted.
[0005] Taiwan Pat. No. M340562 provides a lighting device which
includes top-emitting LEDs mounted on the central region of the top
surface of a circuit board to provide illumination to the front
side of the circuit board, side-emitting LEDs mounted on the
peripheral region of the top surface to provide illumination to the
lateral side of the circuit board, and driver circuitry for driving
the LEDs is mounted on the bottom surface of the circuit board.
Since all the LEDs are disposed on the top surface of the circuit
board, they do not provide illumination to the backside of the
circuit board. Furthermore, the LEDs and the driver circuitry for
driving the LEDs are mounted on the opposite surfaces of the same
circuit board, and thus gather heat within a small area. As a
result, it is hard to provide effective heat dissipation for the
circuit board and the elements mounted thereon, and overheating is
likely to occur, thereby shortening the lifetime and impairing the
reliability of the lighting device.
[0006] Therefore, it is desired an LED bulb which has a wide
lighting angle and multiple light-emitting directions, can
effectively dissipate heat so as to maintain the lifetime of the
LEDs thereof, is reliable in terms of structure and design, and
incurs low production costs.
SUMMARY OF THE INVENTION
[0007] An object of the present invention is to provide an LED bulb
having an increased lighting angle and light-emitting
directions.
[0008] Another object of the present invention is to provide a
highly reliable LED bulb.
[0009] Yet another object of the present invention is to provide a
low cost LED bulb.
[0010] According to the present invention, an LED bulb includes a
member joined to or utilized to combine a housing and a bulb base
together, a stem having a first lead frame and a second lead frame
extending from the stem into a cavity of the housing, and at least
one LED strip suspended between the first and second lead frames.
The first and second lead frames of the stem are electrically
connected to the bulb base and the at least one LED strip, to
provide power to the at least one LED strip. Each of the at least
one LED strip includes a substrate mounted with top-emitting LEDs
and side-emitting LEDs thereon. The top-emitting LEDs have a
light-emitting direction substantially perpendicular to the
mounting surface of the substrate that they are mounted thereon,
and the side-emitting LEDs have a light-emitting direction
substantially parallel to the mounting surface of the substrate
that they are mounted thereon.
[0011] Preferably, the side-emitting LEDs are mounted on the
peripheral region of the mounting surface of the substrate that
they are mounted thereon, to provide lateral light and thereby
increase the lighting angle of the LED bulb, resulting in wide and
uniform illumination. In addition, by using the lead frames to
support the at least one LED strip, the LED bulb may have higher
reliability and less production costs.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] These and other objects, features and advantages of the
present invention will become apparent to those skilled in the art
upon consideration of the following description of the preferred
embodiments of the present invention taken in conjunction with the
accompanying drawings, in which:
[0013] FIG. 1 shows a sectional view taken along the longitudinal
axis of the LED bulb according to a first embodiment of the present
invention;
[0014] FIG. 2 is an exploded view of the LED bulb as shown in FIG.
1;
[0015] FIG. 3 is an illustrative circuit diagram of the LED bulb as
shown in FIG. 1;
[0016] FIG. 4 shows an LED bulb according to a second embodiment of
the present invention;
[0017] FIG. 5 is a perspective view of a LED strip of the present
invention;
[0018] FIG. 6 is a side view of the LED strip as shown in FIG.
5;
[0019] FIG. 7 shows a first embodiment of the LED strip of the
present invention; and
[0020] FIG. 8 shows a second embodiment of the LED strip of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0021] FIG. 1 shows an LED bulb 100 according to an embodiment of
the present invention; FIGS. 2 and 3 show the exploded view and
circuit diagram of the LED bulb 100 of the present invention. The
LED bulb 100 includes a housing 110 and a bulb base 150 joined to
or combined together by a member 140. In this embodiment, the
housing 110 has an end 114 inserting into a groove 144 of the
member 140, with a securing medium 170, for example a glue, filled
in the groove 144 to secure the housing 110 at the front side of
the member 140, and the bulb base 150 is secured at the rear side
of the member 140, for example, by means of snug fit or adhesive.
As is well known, the bulb base 150 has two electrodes to be
connected to an external power source 230, and the housing 110 has
a cavity 112 for containing a filament. A stem 130 has lead frames
131 and 132 extending from the front end 134 of the stem 130 into
the cavity 112 of the housing 110, and an LED strip 120 is
suspended between the lead frames 131 and 132 and has electrodes
121 and 122 electrically connected to the lead frames 131 and 132
respectively. Preferably, the lead frame 131 of the stem 130
extends into the cavity 112 away from the lead frame 132 of the
stem 130 at a distance greater than or equal to the length of the
substrate 310 of the LED strip 120. In this embodiment, the stem
130 supports the LED strip 120 in the cavity 112 of the housing 110
and supplies power to the LED strip 120 by the electrodes 121 and
122. The housing 110 has an end opening 116 to allow the lead
frames 131 and 132 to place into the cavity 112. Through the rear
end 136 of the stem 130, the lead frames 131 and 132 are
electrically connected to the electrodes of the bulb base 150 by
wires 133 and 135 respectively, to deliver power from the external
power source 230 through the bulb base 150 and the lead frames 131,
132 to the LED strip 120. Preferably, a power control unit 160 is
connected between the electrode 152 of the bulb base 150 and the
wire 135, to limit the voltage or power supplied to the LED strip
120. In this embodiment, the stem 130 is secured to the member 140,
for example, by applying a securing medium 180, such as glue,
between the member 140 and the stem 130, so that the member 140 may
support the stem 130. The member 140 has a front-side opening 142
to allow the stem 130 passing therethrough, and a beck-side opening
146 to allow the wires 133 and 135 passing therethrough. The bulb
base 150 has a top opening 154 to allow the power control unit 160
and/or the wires 133 and 135 to pass through.
[0022] In an embodiment, the power control unit 160 includes a
voltage step-down or clamp element, such as a resistor, to control
the voltage or power supplied to the LED strip 120 within a
predetermined range. It is understood that the power control unit
160 may be dispensed with in another embodiment, depending on the
number and power demands of the LEDs mounted on the LED strip
120.
[0023] In other embodiments, either or both of the housing 110 and
the stem 130 are secured to the member 140 by gluing, thermal
fusion, pressing, snug fit, or screw engagement. In some
embodiments, the electrodes 121 and 122 of the LED strip 120 are
electrically connected to the lead frames 131 and 132 of the stem
130 by soldering, gluing with an electrically conductive adhesive,
hook engagement, or winding.
[0024] Preferably, each of the lead frames 131 and 132 has a
slender shape, for example, in the form of electrically conductive
metal wires or rods, so as to be easily adjusted in its dimension
to pass through the end openings of different apertures and be
received in the housings of various sizes. Preferably, the slender
shape of the lead frames 131 and 132 has an upper width greater
than a lower width thereof, and both the upper and lower widths are
smaller than or equal to the width of the end opening 116 of the
housing 110. When current is supplied from the external power
source 230 to the LED strip 120 through the bulb base 150, the
current flows into the LED strip 120 via the lead frame 131 and
exits the LED strip 120 via the lead frame 132, or, alternatively,
flows into the LED strip 120 via the lead frame 132 and exits the
LED strip 120 via the lead frame 131. It is understood that the
configurations of the lead frames 131 and 132 may be modified in
variant embodiments of the present invention. For instance, the
lead frames 131 and 132 may be curved or bent, solid or hollow.
[0025] More LED strips 120 may be used in different embodiments
according to practical demands enhancing the applications of the
LED bulb 100. As shown in FIG. 4 for another embodiment of the
present invention, an LED bulb 200 includes two LED strips 120 and
120' adjacent to each other and both electrically connected to the
lead frames 131 and 132 by their electrodes 121, 122 and 121',
122'. It is understood that, in a variant embodiment of the present
invention, there may be more than two LED strips supported in the
cavity 112 by the stem 130 so as to increase the brightness of an
LED bulb. In this embodiment, the LED strips 120 and 120' may be
suspended between the lead frames 131 and 132 in a face-to-face
manner or in a side-by-side manner. In an embodiment, the
electrodes 121, 122, and 121', 122' of the LED strips 120, 120' are
electrically connected to the lead frames 131, 132 of the stem 130
by soldering, gluing with an electrically conductive adhesive, hook
engagement, or winding.
[0026] FIG. 5 is a perspective view of the LED strip 120, and FIG.
6 is a side-view of the LED strip 120 as shown in FIG. 5. The LED
strip 120 includes top-emitting LEDs 320 and side-emitting LEDs 330
mounted on the substrate 310. Each of the top-emitting LEDs 320 has
a light-emitting direction perpendicular to the mounting surface of
the substrate 310 that it is mounted on, and each of the
side-emitting LEDs 330 has a light-emitting direction parallel to
the mounting surface of the substrate 310 that it is mounted on.
Preferably, the top-emitting LEDs 320 are mounted in the central
regions of the opposite mounting surfaces of the substrate 310, and
the side-emitting LEDs 330 are mounted in the peripheral regions of
the mounting surfaces in a manner surrounding the top-emitting LEDs
320 on the same mounting surfaces, so that the LED strip 120 may
provide light emitted by the side-emitting LEDs 330 in multiple
lateral directions 360, 361, 362, and 363, and light emitted by the
top-emitting LEDs 320 in the forward direction 366 and the backward
direction 364. Consequently, the planar LED strip 120 is capable of
multi-direction light emission and a wide lighting angle that
contribute to extensive and uniform illumination. In this
embodiment, the top-emitting LEDs 320 and the side-emitting LEDs
330 both include surface mounted LEDs.
[0027] Referring to FIG. 5, in an embodiment, the substrate 310
includes conductors 123 and 125 electrically connected to the
electrodes 121 and 122 respectively, to provide power to the
top-emitting LEDs 320 and the side-emitting LEDs 330 mounted on the
substrate 310. The conductors 123 and 125 include conductive pads,
such as metal pads, through which current may flow from the
electrode 121 or 122 to the top-emitting LEDs 320 and the
side-emitting LEDs 330. In an embodiment, the conductors 123 and
125 are coplanar to a mounting surface of the substrate 310; in
another embodiment, the conductors 123 and 125 are on the opposite
mounting surfaces of the substrate 310 respectively. The electrodes
121 and 122 may be electrically connected to the conductors 123 and
125 by welding, soldering, gluing with an electrically conductive
adhesive, or hook engagement. Current may flow from the electrode
121 to the top-emitting LEDs 320 and the side-emitting LEDs 330
through the conductor 123 and exit the LED strip 120 through the
conductor 125 and the electrode 122, or, alternatively, from the
electrode 122 to the top-emitting LEDs 320 and the side-emitting
LEDs 330 through the conductor 125 and exit the LED strip 120
through the conductor 123 and the electrode 121. Thus, the LED
strip 120 is safe and reliable in terms of structure and
design.
[0028] In an embodiment, as shown in FIG. 7, the substrate 310
includes a double-sided circuit board 410, and the opposite
mounting surfaces 412 and 414 thereof are mounted with some of the
top-emitting LEDs 320 and some of the side-emitting LEDs 330
respectively. In an embodiment, the top-emitting LEDs 320 and the
side-emitting LEDs 330 are divided into two groups, one group of
the top-emitting LEDs 320 and the side-emitting LEDs 330 are
mounted on the mounting surface 412, and the other group of the
top-emitting LEDs 320 and the side-emitting LEDs 330 are mounted on
the other mounting surface 414. The double-sided circuit board 410
may be a rigid printed circuit board or a flexible printed circuit
board. In another embodiment, as shown in FIG. 8, the substrate 310
includes two single-sided circuit boards 420 and 430 attached to
each other in a back-to-back manner. The top-emitting LEDs 320 and
the side-emitting LEDs 330 are divided into two groups, one group
of the top-emitting LEDs 320 and the side-emitting LEDs 330 are
mounted on the mounting surface 422 of the single-sided circuit
board 420, and the other group of the top-emitting LEDs 320 and the
side-emitting LEDs 330 are mounted on the mounting surface 434 of
the single-sided circuit board 430. The backside surface 424 of the
single-sided circuit board 420 is attached to the backside surface
432 of the single-sided circuit board 430. The single-sided circuit
boards 420, 430 may be rigid printed circuit boards or flexible
printed circuit boards. It is understood that, in another
embodiment, all the top-emitting LEDs 320 may be mounted on the
mounting surface 422 of the single-sided circuit board 420, and all
the side-emitting LEDs 330 may be mounted on the mounting surface
434 of the single-sided circuit board 430.
[0029] Referring to FIG. 5 again, by mounting the side-emitting
LEDs 330 in the peripheral regions of the opposite mounting
surfaces of the substrate 310, the LED strip 120 can emit light in
multiple lateral directions and thereby provide extensive and
uniform illumination. Even if fewer LEDs are used for the LED strip
120, a wide lighting angle is still achievable. Therefore, the
dimension of the substrate 310 as well as the number of the
top-emitting LEDs 320 and the side-emitting LEDs 330 can be
adjusted according to practical demands, so that the LED strip 120
is flexibly applicable to bulbs of different sizes, such as bulbs
with standard bulb bases E10, E12, E14, E17, E26, E27, B15, B22,
and GU-10. Compared with the conventional LED bulbs using
through-hole LEDs as the light source, the LED bulb according to
the present invention using the LED strip 120 with surface mounted
LEDs or chip-on-board LEDs as its light source has higher
structural stability and enhanced safety in current control. As the
surface mounted LEDs are available in both the top-emitting type
and the side-emitting type, and have higher mounting speed, higher
production yield, lower costs, and fewer components than the
through-hole LEDs, the LED bulb according to the present invention
features multiple light-emitting directions, high assembly speed,
high production yield, low costs, and fewer components.
Furthermore, if surface mounted LEDs, which are smaller than
through-hole LEDs, are used for the LED strip 120, the LED bulb
according to the present invention can be made in a variety of
dimensions while production costs are also effectively reduced.
[0030] Referring to FIGS. 1, 3, and 5, the top-emitting LEDs 320
and the side-emitting LEDs 330 are divided into two lighting groups
210 and 220 that are parallel connected between the lead frames 131
and 132. As shown in FIG. 3, where the external power source 230 is
an alternating-current (AC) power source, the lighting group 210
establishes a first circuitry forward biased from the lead frame
131 to the lead frame 132, and the lighting group 220 establishes a
second circuitry forward biased from the lead frame 132 to the lead
frame 131. Thus, the top-emitting LEDs 320 and the side-emitting
LEDs 330 in the lighting group 210 are lit during the positive half
cycle of the AC power source 230, and the top-emitting LEDs 320 and
the side-emitting LEDs 330 in the lighting group 220 are lit during
the negative half cycle of the AC power source 230. As a result,
the lighting groups 210, 220 will emit light alternately. In an
embodiment, the top-emitting LEDs 320 and the side-emitting LEDs
330 in the lighting group 210 are mounted on one mounting surface
of the substrate 310, and the top-emitting LEDs 320 and the
side-emitting LEDs 330 in the lighting group 220 are mounted on the
opposite mounting surface of the substrate 310, so that the LED
strip 120 is capable of alternate light emission from its two
mounting surfaces. In another embodiment, the top-emitting LEDs 320
and the side-emitting LEDs 330 in the lighting group 210 are
mounted on an upper portion of the substrate 310, and the
top-emitting LEDs 320 and the side-emitting LEDs 330 in the
lighting group 220 are mounted on a lower portion of the substrate
310, so that the LED strip 120 can emit light from its upper and
lower portions by turns. Alternatively, the lighting group 210
includes all the top-emitting LEDs 320 mounted on the substrate
310, and the lighting group 220 includes all the side-emitting LEDs
330 mounted on the substrate 310.
[0031] Similarly, as shown in FIGS. 3-5, where the LED bulb 200
includes the LED strips 120 and 120', the top-emitting LEDs 320 and
the side-emitting LEDs 330 of the LED strips 120 and 120' may be
divided into the lighting groups 210 and 220. In an embodiment, the
lighting group 210 includes the top-emitting LEDs 320 and the
side-emitting LEDs 330 mounted on the LED strip 120, and the
lighting group 220 includes the top-emitting LEDs 320 and the
side-emitting LEDs 330 mounted on the LED strip 120', thus allowing
the LED strips 120 and 120' to emit light by turns. In another
embodiment, the lighting group 210 includes all the top-emitting
LEDs 320 of the LED strips 120 and 120', and the lighting group 220
includes all the side-emitting LEDs 330 of the LED strips 120 and
120'.
[0032] As shown in the above embodiments, the present invention
uses a planar LED strip to achieve the object of increasing the
lighting angle of an LED bulb. Compared with the arts using a
three-dimensional array of LEDs to achieve the same object, the
present invention advantageously employs fewer components, can be
assembled more easily, has a higher production yield, and requires
lower production costs. In addition, even if a small number of the
LEDs fail during use, the LED bulb can still function normally,
thus providing high economic benefits.
[0033] The lead frames disclosed herein not only support the LED
strip, but also supply power from the external power source to the
LED strip. Hence, the lead frames of the LED bulb according to the
present invention can be formed as their counterparts in standard
bulbs so as to be compatible with the shapes of existing glass
bulbs and the Edison screw bulb bases. By grouping the LEDs into
two opposite polarity directions to be driven by an AC power source
directly or under the limitation of the power control unit, there
will be no need of power converters, for example AC-to-DC
converters, and consequently the reliability and component safety
of the LED bulb are increased while the costs of the LED bulb are
further reduced.
[0034] The foregoing description and disclosure only serve to
demonstrate the principle and features of the present invention and
are not intended to limit the scope of the present invention, which
is defined by the appended claims. It is understood that all
equivalent modifications, changes, and combination of the disclosed
components should be encompassed by the appended claims. In
addition, as the words "a", "an", and "one" used in the description
and disclosure of the present invention and the appended claims
connote "at least one", changes in the number of the disclosed
components should also fall within the scope of the present
invention.
* * * * *